Coil device

Abstract

To provide a coil device which facilitates secure of a mounting strength and can prevent generation of a short circuit failure between a leading part and a wiring part.SOLUTION: A coil device 1 includes: a core 10 that contains a magnetic material, and includes a mounting surface 15 and a third side surface 13 that is extended in a direction vertical to the mounting surface 15; and a wire 20 that includes a winding part 21 that is arranged in an inner part of the core 10, and a leading part 22a that is led from the winding part 21. The leading part 22a includes: a base end part 23 that is continued to the winding part 21; and a flat part 24 that is continued to the base end part 23, and is crushed in a flat shape. The flat part 24 includes: an embedded part 240 that is arranged in the inner part of the core 10; and a terminal part 242 that has a plating layer 30 and is arranged at an external part of the core 10. The embedded part 240 is extended obliquely toward a third side surface 13 from the base end part 23. The terminal part 242 is exposed from the core 10 at a center part of the third side surface 13 in a direction vertical to the mounting surface 15, and is extended toward the mounting surface 15 from the center part of the third side surface 13.SELECTED DRAWING: Figure 4A

Description

Technical Field

[0001] The present disclosure relates to a coil device.

Background Art

[0002] For example, Patent Document 1 discloses a coil device that can be used as an inductor. The coil device of Patent Document 1 has a winding portion disposed inside a core and a lead-out portion drawn from the winding portion. The lead-out portion has a flattened portion flattened into a flat shape, and is drawn from the winding portion toward the side surface of the core. A part of the flattened portion is disposed inside the core. The remaining part of the flattened portion is exposed from the core and extends along the side surface and the mounting surface of the core.

[0003] In the coil device of Patent Document 1, the flattened portion disposed on the mounting surface can be connected to a mounting substrate by a conductive bonding material (such as solder or a conductive adhesive). In this way, since the flattened portion functions as a terminal of the coil device, it is not necessary to separately provide a terminal for the coil device, and the coil device can be miniaturized and the number of components can be reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the coil device of Patent Document 1, inside the core, the flat portion is partially drawn out along the outer peripheral surface of the winding portion so as to be adjacent to the winding portion. Therefore, when the distance between the flat portion and the winding portion becomes short due to miniaturization of the coil device, there is a risk of a short circuit failure occurring between the flat portion and the winding portion. Further, in the coil device of Patent Document 1, since the area of the flat portion disposed on the side surface of the core is small, it is difficult to form a fillet such as solder on the flat portion disposed on the side surface of the core. Therefore, there is a problem that it is difficult to ensure the mounting strength of the coil device.

[0006] The present disclosure provides a coil device that can easily ensure mounting strength and prevent the occurrence of a short circuit failure between the lead-out portion and the winding portion.

Means for Solving the Problems

[0007] The coil device of the present disclosure includes a core including a magnetic material and having a mounting surface and a side surface extending in a direction perpendicular to the mounting surface, a wire having a winding portion disposed inside the core and a lead-out portion drawn out from the winding portion, the lead-out portion having a base end portion continuous with the winding portion and a flat portion continuous with the base end portion and flattened into a flat shape, the flat portion having an embedded portion disposed inside the core and a terminal portion having a plating layer and disposed outside the core, the embedded portion extending obliquely from the base end portion toward the side surface, the terminal portion being exposed from the core at the central portion of the side surface in a direction perpendicular to the mounting surface and extending from the central portion of the side surface toward the mounting surface.

[0008] The embedded portion may extend from the base end portion to the central portion of the winding portion in a direction perpendicular to the mounting surface.

[0009] The embedded portion may extend obliquely from the base end portion to the side surface without bending at a right angle.

[0010] The base end portion has an inclined portion, and in a cross section perpendicular to the mounting surface and the side surface, the thickness of the inclined portion may become thinner as it approaches the flat portion.

[0011] The lead-out portion is bent at the boundary between the base end portion and the flat portion, and the radius of curvature of the lead-out portion at the boundary may be larger than the thickness of the flat portion.

[0012] The wire is a round wire or a flat wire wound edgewise, and the wound portion may have an insulating coating layer.

[0013] When viewed from a direction perpendicular to the mounting surface, the shape of the outer peripheral surface of the wound portion may be circular.

[0014] The winding axis direction of the wound portion may be inclined with respect to the direction perpendicular to the mounting surface.

Brief Description of the Drawings

[0015]

Figure 1A

Figure 1B

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 5E

Figure 6A

Figure 6B

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be noted that the illustrated content is only schematic and exemplary for understanding the present disclosure, and the appearance and dimensional ratios may be different from the actual ones. Also, the present disclosure is not limited to the following embodiments.

[0017] (First Embodiment) The coil device 1 shown in FIG. 1A is a surface mount type inductor and is mounted, for example, on a power supply circuit of an electronic device. The coil device 1 includes a core 10 and a wire 20 (FIG. 1B). The shape of the core 10 is not particularly limited, but in the example shown in FIG. 1A, it is substantially a hexahedron. The shape of the core 10 may be a cylinder, an elliptical cylinder, an n-sided polyhedron (n≥7), or other polygons. The core 10 has a first side surface 11, a second side surface 12, a third side surface 13, a fourth side surface 14, a mounting surface 15, and a mounting opposing surface 16.

[0018] The ridge line portion between the second side surface 12 and the third side surface 13 is chamfered, and a chamfered portion 19 is formed on the ridge line portion between the second side surface 12 and the third side surface 13. By forming the chamfered portion 19 on the core 10, it becomes easier to identify the orientation of the core 10. However, the chamfered portion 19 is not essential and may be omitted.

[0019] The first side surface 11 and the second side surface 12 face each other. The third side surface 13 and the fourth side surface 14 face each other. The mounting surface 15 and the mounting opposing surface 16 face each other.

[0020] In FIG. 1A etc., the X-axis is an axis along the direction in which the first side surface 11 and the second side surface 12 face each other. The Y-axis is an axis along the direction in which the third side surface 13 and the fourth side surface 14 face each other. The Z-axis is an axis along the direction in which the mounting surface 15 and the mounting opposite surface 16 face each other (the direction perpendicular to the mounting surface 15).

[0021] The X-axis, Y-axis, and Z-axis are perpendicular to each other. Hereinafter, for each of the X-axis, Y-axis, and Z-axis, the direction away from the center of the core 10 is defined as "outer", and the direction approaching the center of the core 10 is defined as "inner". Also, the positive direction side of the Z-axis is defined as "upper", and the negative direction side of the Z-axis is defined as "lower". However, the upper side in the Z-axis direction does not necessarily coincide with the upper side in the vertical direction. Also, the lower side in the Z-axis direction does not necessarily coincide with the lower side in the vertical direction.

[0022] The width of the core 10 in the X-axis direction is not particularly limited, but is, for example, 3.0 to 10.0 mm. The width of the core 10 in the Y-axis direction is not particularly limited, but is, for example, 3.0 to 10.0 mm. The width of the core 10 in the Z-axis direction (the thickness of the core 10) is not particularly limited, but is 2.0 to 10.0 mm.

[0023] The core 10 is composed of a composite material containing a magnetic material and a resin. The method for forming the core 10 is not particularly limited, but is, for example, powder compacting, injection molding, or machining. In this embodiment, the core 10 is a compacted body containing a magnetic material and a resin. The magnetic material constituting the core 10 is not particularly limited, but is, for example, ferrite (Ni-Zn based ferrite, Mn-Zn based ferrite, etc.) or a metal magnetic material. The resin constituting the core 10 is not particularly limited, but is, for example, an epoxy resin or a phenolic resin.

[0024] The core 10 has first recesses 17a and 17b and second recesses 18a and 18b. The first recess 17a and the second recess 18a are continuously formed from the third side surface 13 to the mounting surface 15. The first recess 17b and the second recess 18b are continuously formed from the fourth side surface 14 to the mounting surface 15.

[0025] The first recess 17a is formed on the third side surface 13, and the first recess 17b is formed on the fourth side surface 14. A side portion 244 of a drawing portion 22a to be described later is disposed in the first recess 17a, and a side portion 244 of a drawing portion 22b to be described later is disposed in the first recess 17b. The width of the first recess 17a or 17b in the X-axis direction is wider than the width of the side portion 244 in the X-axis direction.

[0026] The second recesses 18a and 18b are formed on the mounting surface 15. A mounting portion 246 of a drawing portion 22a to be described later is disposed in the second recess 18a, and a mounting portion 246 of a drawing portion 22b to be described later is disposed in the second recess 18b. The width of the second recess 18a or 18b in the X-axis direction is wider than the width of the mounting portion 246 in the X-axis direction. The depth of the second recess 18a or 18b is equal to or less than the thickness of the mounting portion 246. The first recesses 17a and 17b and the second recesses 18a and 18b are not essential and may be omitted from the core 10.

[0027] As shown in FIG. 1B, the wire 20 has a winding portion 21, a drawing portion 22a, and a drawing portion 22b. The wire 20 is, for example, an insulated coated wire in which a conductive core wire is coated with an insulating coating (insulating coating layer). As the wire 20, for example, known windings such as AIW (polyamideimide copper wire), UEW (polyurethane copper wire), and PEW (polyester copper wire) can be employed. The material constituting the wire is not particularly limited, but is, for example, copper, a copper alloy, silver, or nickel. The wire 20 is a round wire, but may be a flat wire (for example, a flat wire wound edgewise). The diameter of the wire 20 is not particularly limited, but is, for example, 0.3 to 2.0 mm.

[0028] The winding portion 21 is an air-core coil and is disposed inside the core 10. As shown in FIG. 2, in the winding portion 21, the wire 20 is wound in a spiral shape with 2.5 turns. The winding axis direction of the winding portion 21 corresponds to the Z-axis direction. The number of layers in the winding axis direction (Z-axis direction) of the winding portion 21 is three layers (see FIG. 4A). However, the number of turns of the wire 20 is not particularly limited and may be 1.5 turns or 3.5 turns or more. Also, the number of layers in the winding axis direction of the winding portion 21 may be two layers or four layers or more. In the winding portion 21, an insulating film (insulating coating layer) is formed on the surface of the wire 20. When viewed from the direction (Z-axis direction) perpendicular to the mounting surface 15, the shape of the outer peripheral surface of the winding portion 21 is circular, but it may also be elliptical or the like.

[0029] The lead-out portion 22a is led out from the third layer in the winding axis direction of the winding portion 21. The lead-out portion 22b is led out from the first layer in the winding axis direction of the winding portion 21 toward the side opposite to the lead-out portion 22a. The lead-out portions 22a and 22b each have a base end portion 23 and a flat portion 24. As shown in FIG. 4A, the lead-out portion 22a has an inner surface 25 facing the mounting surface 15 or the third side surface 13 and an outer surface 26 facing the inner surface 25. Also, the lead-out portion 22b has an inner surface 25 facing the mounting surface 15 or the fourth side surface 14 and an outer surface 26 facing the inner surface 25.

[0030] The base end portion 23 and the flat portion 24 are formed by crushing (pressing or squeezing) the lead-out portion 22a or 22b. The flat portion 24 is the portion where the lead-out portion 22a or 22b is crushed into a flat shape. On the other hand, the base end portion 23 is the portion where the thickness of the lead-out portion 22a or 22b (the thickness between the inner surface 25 and the outer surface 26) gradually becomes thinner as it goes from the winding portion 21 toward the flat portion 24. In other words, the base end portion 23, unlike the flat portion 24, is the portion where the lead-out portion 22a or 22b is not completely crushed. Hereinafter, the details of the base end portion 23 and the flat portion 24 will be described.

[0031] The base end portion 23 has a tapered shape that tapers from the winding portion 21 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. The base end portion 23 is disposed inside the core 10. One end in the extending direction of the base end portion 23 is continuous with the winding portion 21, and the other end in the extending direction of the base end portion 23 is continuous with the flat portion 24. The base end portion 23 of the lead-out portion 22a is located above the center of the core 10 in the Z-axis direction. Also, the base end portion 23 of the lead-out portion 22b is located below the center of the core 10 in the Z-axis direction.

[0032] The base end portion 23 has an inclined portion 230. The inclined portion 230 is disposed inside the core 10. In a cross section perpendicular to the mounting surface 15 and the third side surface 13 (i.e., the YZ cross section), the thickness of the inclined portion 230 (the thickness between the inner surface 25 and the outer surface 26) becomes thinner as it approaches the boundary portion 27a between the base end portion 23 and the flat portion 24. The boundary portion 27a between the base end portion 23 and the flat portion 24 is disposed inside the core 10 and is not exposed from the core 10.

[0033] As shown in FIG. 3, when viewed from the direction perpendicular to the mounting surface 15 (i.e., the Z-axis direction), the width of the inclined portion 230 in the X-axis direction becomes wider as it approaches the boundary portion 27a (FIG. 4A) between the base end portion 23 (the inclined portion 230) and the flat portion 24.

[0034] As shown in FIG. 4A, an inclined surface 231a is formed on the inner surface 25 of the inclined portion 230. The inclined surface 231a inclines toward the side opposite to the mounting surface 15 (the mounting-opposing surface 16 side or upward) as it approaches the boundary portion 27a between the base end portion 23 and the flat portion 24. At the center of the inclined surface 231a in the Y-axis direction, the inclination angle of the inclined surface 231a with respect to the mounting surface 15 is not particularly limited, but is, for example, 10° or more and less than 90° or 30° or more and less than 90°. The inclined surface 231a is a curved surface, but may also be a flat surface.

[0035] On the outer surface 26 of the inclined portion 230, an inclined surface 231b is formed. The inclined surface 231b is inclined toward the mounting surface 15 side (downward) as it approaches the boundary portion 27a between the base end portion 23 and the flat portion 24. At the center of the inclined surface 231b in the Y-axis direction, the inclination angle of the inclined surface 231b with respect to the mounting facing surface 16 is not particularly limited, but is, for example, 10° or more and less than 90°, or 30° or more and less than 90°. The inclined surface 231b is a curved surface, but may also be a flat surface.

[0036] At the base end portion 23 (inclined portion 230), the coating of the wire 20 is not peeled off, and the surface of the base end portion 23 (inclined portion 230) is covered by the coating. However, at least a part of the base end portion 23 (inclined portion 230) may have the coating of the wire 20 peeled off.

[0037] Although detailed illustration is omitted, the inclined portion 230 may have an inclined surface 231a while not having the inclined surface 231b. Alternatively, the inclined portion 230 may have the inclined surface 231b while not having the inclined surface 231a.

[0038] As shown in FIG. 4B, in addition to the inclined portion 230, the base end portion 23 may have a non-inclined portion 232. The non-inclined portion 232 is located between the winding portion 21 and the inclined portion 230. Unlike the inclined portion 230, the non-inclined portion 232 is a portion where the lead-out portion 22a or 22b is not crushed. Therefore, the diameter of the wire 20 in the non-inclined portion 232 is equal to the diameter of the wire 20 in the winding portion 21.

[0039] As shown in FIG. 4A, the flat portion 24 is continuous with the base end portion 23 and is crushed into a flat shape. As shown in FIG. 2, the flat portion 24 has a flat shape and is formed wider in the X-axis direction than the diameter Φ of the wire 20. The width W in the X-axis direction of the flat portion 24 shown in FIG. 2 is not particularly limited, but is, for example, 1 to 10 mm. The ratio W / Φ of the width W in the X-axis direction of the flat portion 24 to the diameter (however, the diameter of the wire 20 in the winding portion 21) Φ of the wire 20 is not particularly limited, but is, for example, 1 < W / Φ ≦ 10, or 2 ≦ W / Φ ≦ 8.

[0040] The thickness of the flat portion 24 is not particularly limited, but is, for example, 0.05 to 0.5 mm. The ratio T / Φ of the thickness T of the flat portion 24 to the diameter of the wire 20 (however, the diameter of the wire 20 in the winding portion 21) is not particularly limited, but is, for example, 1 / 15 ≤ T / Φ ≤ 1 / 2, or 1 / 10 ≤ T / Φ ≤ 1 / 3.

[0041] The thickness of the flat portion 24 (the thickness between the inner surface 25 and the outer surface 26) is substantially constant along the extending direction of the flat portion 24. However, "substantially constant" means that the error of the thickness of the flat portion 24 is within several percent to several tens of percent (not particularly limited, but for example, ±10%, or ±5%, or ±3%).

[0042] As shown in FIG. 4A, the lead-out portion 22a or 22b is bent at the boundary portion 27a between the base end portion 23 and the flat portion 24. At the boundary portion 27a between the base end portion 23 and the flat portion 24, the radius of curvature of the lead-out portion 22a is not particularly limited, but is larger than the thickness of the flat portion 24. Also, at the boundary portion 27a between the base end portion 23 and the flat portion 24, the radius of curvature of the lead-out portion 22b is not particularly limited, but is larger than the thickness of the flat portion 24. However, in FIG. 4A, since the thickness of the flat portion 24 is shown relatively thick, the radius of curvature of the lead-out portion 22a or 22b is shown smaller than the thickness of the flat portion 24 at the boundary portion 27a. At the boundary portion 27a, the radius of curvature of the lead-out portion 22a or 22b may be equal to the thickness of the flat portion 24, or may be smaller than the thickness of the flat portion 24.

[0043] The flat portion 24 has an embedded portion 240 and a terminal portion 242. The embedded portion 240 is disposed inside the core 10. In the embedded portion 240, the coating of the wire 20 is not peeled off, and the surface of the embedded portion 240 is covered with the coating of the wire 20. The embedded portion 240 extends obliquely from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10 so as to bend with respect to the base end portion 23. In the example shown in FIG. 4A, the entire region along the extending direction of the embedded portion 240 is inclined with respect to the side surface of the core 10, but a part along the extending direction of the embedded portion 240 may be inclined with respect to the side surface of the core 10.

[0044] The extending direction of the embedded portion 240 is inclined with respect to the direction perpendicular to the mounting surface 15 (Z-axis direction). Further, the extending direction of the embedded portion 240 is inclined with respect to the winding axis direction (Z-axis direction) of the winding portion 21. Further, the extending direction of the embedded portion 240 is inclined with respect to the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. Further, the extending direction of the embedded portion 240 is inclined with respect to the mounting surface 15 and the mounting opposing surface 16.

[0045] In the vicinity of the boundary portion 27a between the base end portion 23 and the flat portion 24, the inclination angle of the embedded portion 240 with respect to the winding axis direction (Z-axis direction) of the winding portion 21 or the direction perpendicular to the mounting surface 15 (Z-axis direction) is not particularly limited, but is, for example, 5° or more and less than 90°, 10° or more and less than 80°, or 20° or more and less than 70°. The same applies to the vicinity of the boundary portion 27b between the embedded portion 240 and the terminal portion 242. Further, the same applies to the central portion in the extending direction of the embedded portion 240.

[0046] In the vicinity of the boundary portion 27a between the base end portion 23 and the flat portion 24, the inclination angle of the embedded portion 240 with respect to the side surface (the third side surface 13 or the fourth side surface 14) of the core 10 is not particularly limited, but is, for example, 5° or more and less than 90°, 10° or more and less than 80°, or 20° or more and less than 70°. The same applies to the vicinity of the boundary portion 27b between the embedded portion 240 and the terminal portion 242. Further, the same applies to the central portion in the extending direction of the embedded portion 240.

[0047] The embedded portion 240 extends linearly from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. However, the embedded portion 240 may extend while being bent or curved so as not to bend at a right angle from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. However, in the present embodiment, the “right angle” is not limited to only a strict right angle (that is, 90°), and a state deviated by several degrees (not particularly limited, for example, 3 degrees) or less from the strict right angle is also included in the concept of “right angle”.

[0048] For example, the embedded portion 240 may be bent or curved so as to be convex toward the mounting surface 15 as a whole from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. Alternatively, the embedded portion 240 may be bent or curved so as to be convex toward the mounting opposite surface 16 as a whole from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. Alternatively, the embedded portion 240 may be bent or curved so as to undulate in a wave shape from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10.

[0049] The inclination angle of the embedded portion 240 of the lead-out portion 22a with respect to the winding axis direction (Z-axis direction) of the winding portion 21 or the direction perpendicular to the mounting surface 15 (Z-axis direction) is substantially equal to the inclination angle of the embedded portion 240 of the lead-out portion 22b with respect to the winding axis direction (Z-axis direction) of the winding portion 21 or the direction perpendicular to the mounting surface 15 (Z-axis direction). However, "substantially equal" is a concept that includes not only the case where the former inclination angle completely coincides with the latter inclination angle, but also the case where the former inclination angle differs from the latter inclination angle by within ±3°. The former inclination angle may be smaller than the latter inclination angle, or may be larger than the latter inclination angle.

[0050] The embedded portion 240 of the lead-out portion 22a extends so as to descend from the base end portion 23 toward the central portion in the Z-axis direction of the third side surface 13. The embedded portion 240 of the lead-out portion 22b extends so as to ascend from the base end portion 23 toward the central portion in the Z-axis direction of the fourth side surface 14. However, the central portion in the Z-axis direction of the third side surface 13 or the fourth side surface 14 is not limited to only the exact center in the Z-axis direction of the third side surface 13 or the fourth side surface 14, but also includes positions vertically spaced apart from the exact center by a predetermined length. Here, the predetermined length is not particularly limited, but is, for example, a length corresponding to 10% or less, 8% or less, 5% or less, or 3% or less of the height H of the core 10 shown in FIG. 4A.

[0051] The embedded portion 240 extends from the base end portion 23 to the central portion of the winding portion 21 in the direction perpendicular to the mounting surface 15 (Z-axis direction). Here, the central portion of the winding portion 21 in the Z-axis direction is not limited to only the exact center in the Z-axis direction of the winding portion 21, but also includes positions spaced vertically by a predetermined length from the exact center. Here, the predetermined length is not particularly limited, but for example, it corresponds to a length of 10% or less, 8% or less, 5% or less, or 3% or less of the height along the winding axis direction of the winding portion 21. In the example shown in FIG. 4A, the embedded portion 240 extends from the base end portion 23 of the first layer or the third layer of the winding portion 21 to the second layer of the winding portion 21 in the direction perpendicular to the mounting surface 15 (Z-axis direction).

[0052] In the present embodiment, the central portion of the winding portion 21 in the Z-axis direction is located at the central portion of the core 10 in the Z-axis direction. However, the central portion of the winding portion 21 in the Z-axis direction may be located above the central portion of the core 10 in the Z-axis direction, or may be located below this.

[0053] The terminal portion 242 is continuous with the embedded portion 240 and is disposed outside the core 10. The terminal portion 242 extends along the side surface (the third side surface 13 or the fourth side surface 14) and the mounting surface 15 of the core 10. In the terminal portion 242, the coating of the wire 20 is peeled off, and the surface of the terminal portion 242 is not covered with the coating of the wire 20. In the vicinity of the boundary portion 27b between the embedded portion 240 and the terminal portion 242, the terminal portion 242 is bent with respect to the embedded portion 240 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. The boundary portion 27b between the embedded portion 240 and the terminal portion 242 is not disposed inside the core 10 and is exposed from the core 10.

[0054] The flat portion 24 is bent at the boundary portion 27b between the embedded portion 240 and the terminal portion 242. At the boundary portion 27b between the embedded portion 240 and the terminal portion 242, the radius of curvature of the flat portion 24 is not particularly limited, but is larger than the thickness of the flat portion 24. However, at the boundary portion 27b between the embedded portion 240 and the terminal portion 242, the radius of curvature of the flat portion 24 may be equal to the thickness of the flat portion 24, or may be smaller than the thickness of the flat portion 24.

[0055] The terminal portion 242 has a side portion 244 and a mounting portion 246. The side portion 244 is continuous with the embedded portion 240 and is bent with respect to the embedded portion 240. The side portion 244 is exposed from the core 10 at the central portion of the side surface (the third side surface 13 or the fourth side surface 14) of the core 10 in the direction perpendicular to the mounting surface 15 (Z-axis direction). And the side portion 244 extends along the side surface (the third side surface 13 or the fourth side surface 14) of the core 10 from the central portion of the side surface (the third side surface 13 or the fourth side surface 14) of the core 10 toward the mounting surface 15.

[0056] The side portion 244 is arranged parallel to the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. In this embodiment, "parallel" is not limited to strict parallelism only, and a state where it is deviated by several degrees (not particularly limited, for example, 3 degrees) or less with respect to strict parallelism is also included in the concept of "parallel". Also, "perpendicular" is not limited to strict perpendicularity only, and a state where it is deviated by several degrees (not particularly limited, for example, 3 degrees) or less with respect to strict perpendicularity is also included in the concept of "perpendicular".

[0057] The side portion 244 is in contact with the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. However, the side portion 244 does not have to be in contact with the side surface of the core 10, and a gap may be formed between the side portion 244 and the side surface of the core 10. In the example shown in FIG. 4A, the entire side portion 244 is in contact with the side surface of the core 10, but a part of the side portion 244 may be in contact with the side surface of the core 10.

[0058] The length of the side portion 244 along the Z-axis is approximately equal to 1 / 2 of the height H of the core 10. However, "approximately equal" is a concept that includes not only the case where the length of the side portion 244 along the Z-axis completely coincides with 1 / 2 of the height H of the core 10, but also the case where the length of the side portion 244 along the Z-axis differs within ±5% with respect to 1 / 2 of the height H of the core 10.

[0059] The side portion 244 extends obliquely with respect to the embedded portion 240. Also, the side portion 244 extends linearly from the boundary portion 27b between the embedded portion 240 and the terminal portion 242 toward the mounting surface 15. However, the side portion 244 may extend while being bent or curved from the boundary portion 27b between the embedded portion 240 and the terminal portion 242 toward the mounting surface 15.

[0060] The mounting portion 246 is continuous with the side portion 244 and extends in a direction orthogonal to the side portion 244. The mounting portion 246 extends along the mounting surface 15. The mounting portion 246 is a portion that is connected to a mounting substrate (not shown) by a conductive bonding material (such as solder or a conductive adhesive).

[0061] As shown in FIG. 1A, the mounting portion 246 of the lead-out portion 22a is disposed in the second recess 18a formed in the mounting surface 15. Also, the mounting portion 246 of the lead-out portion 22b is disposed in the second recess 18b formed in the mounting surface 15. Also, the side portion 244 of the lead-out portion 22a is disposed in the first recess 17a formed in the third side surface 13. Also, the side portion 244 of the lead-out portion 22b is disposed in the first recess 17b formed in the fourth side surface 14.

[0062] As shown in FIG. 4A, plating layers 30 are formed on the inner surface 25 and the outer surface 26 of the lead-out portion 22a. Also, plating layers 30 are formed on the inner surface 25 and the outer surface 26 of the lead-out portion 22b. The plating layers 30 are formed on the portions of the lead-out portion 22a or 22b that are exposed from the core 10, that is, on the terminal portion 242. By forming the plating layer 30 on the outer surface 26 of the terminal portion 242, the adhesiveness of the bonding material (for example, solder or a conductive adhesive) to the outer surface 26 is improved when the coil device 1 is mounted. The plating layer 30 may be a single layer or a multi-layer. The plating layer 30 is not particularly limited, and examples thereof include Cu plating, Ni plating, Sn plating, Ni-Sn plating, Cu-Ni-Sn plating, Ni-Au plating, Au plating, and Sn-Pb plating (solder plating).

[0063] The plating layer 30 is formed on both the inner surface 25 and the outer surface 26 of the terminal portion 242. However, the plating layer 30 may not be formed on the inner surface 25 of the terminal portion 242 (side portion 244 or mounting portion 246), and may be formed on the outer surface 26 of the terminal portion 242 (side portion 244 or mounting portion 246). In this case, the inner surface 25 of the terminal portion 242 (side portion 244 or mounting portion 246) may be covered with the coating of the wire 20.

[0064] The plating layer 30 is formed on both the side portion 244 and the mounting portion 246 of the terminal portion 242. However, the plating layer 30 may be formed on the mounting portion 246 while not being formed on the side portion 244. In this case, the side portion 244 may be covered with the coating of the wire 20.

[0065] The plating layer 30 is not formed on the embedded portion 240 disposed inside the core 10 among the flat portions 24. Also, the plating layer 30 is not formed on the base end portion 23 disposed inside the core 10. However, the plating layer 30 may be formed on the inner surface 25 and / or the outer surface 26 of the embedded portion 240. Also, the plating layer 30 may be formed on the inner surface 25 and / or the outer surface 26 of the base end portion 23.

[0066] Next, a method for manufacturing the coil device 1 shown in FIG. 1B will be described with reference to FIGS. 5A to 5E and the like. First, as shown in FIG. 5A, a wire 20 having a winding portion 21 and lead portions 22a and 22b drawn out from the winding portion 21 is prepared. The wire 20 is a round wire, but may also be a flat wire. The winding portion 21 is an air-core coil, and the lead portions 22a and 22b are drawn out from the winding portion 21 toward opposite sides.

[0067] Next, as shown in FIG. 5B, the lead-out portion 22a is crushed to form a flat flat portion 24 and an inclined inclined portion 230 (see FIG. 4A) in the lead-out portion 22a. The inclined portion 230 has a thickness (the thickness between the inner surface 25 and the outer surface 26) that gradually decreases as it goes from the winding portion 21 toward the flat portion 24. The range in which the lead-out portion 22a is crushed is, for example, the range from the boundary portion 22a1 between the winding portion 21 and the lead-out portion 22a to the tip portion 22a2 of the lead-out portion 22a. As a result, a base end portion 23 having the inclined portion 230 shown in FIG. 4A is formed around the boundary portion 22a1 between the winding portion 21 and the lead-out portion 22a. Also, a flat portion 24 is formed on the tip side of the lead-out portion 22a with respect to the base end portion 23.

[0068] Also, as shown in FIG. 5B, the lead-out portion 22b is crushed to form a flat flat portion 24 and an inclined inclined portion 230 (see FIG. 4A) in the lead-out portion 22b. The inclined portion 230 has a thickness that gradually decreases as it goes from the winding portion 21 toward the flat portion 24. The range in which the lead-out portion 22b is crushed is, for example, the range from the boundary portion 22b1 between the winding portion 21 and the lead-out portion 22b to the tip portion 22b2 of the lead-out portion 22b. As a result, a base end portion 23 having the inclined portion 230 shown in FIG. 4A is formed around the boundary portion 22b1 between the winding portion 21 and the lead-out portion 22b. Also, a flat portion 24 is formed on the tip side of the lead-out portion 22b with respect to the base end portion 23.

[0069] Next, as shown in FIG. 5C, the flat portion 24 of the lead-out portion 22a is bent at two locations. First, at the boundary portion 27a between the base end portion 23 and the flat portion 24, the horizontally extending flat portion 24 (see FIG. 5B) is bent downward. As a result, as shown in FIG. 5C, the flat portion 24 extends obliquely downward with respect to the base end portion 23. Also, for example, on the winding portion 21 side rather than at the center in the extending direction of the flat portion 24, the flat portion 24 (the portion shown by the broken line in FIG. 5C) is bent upward (in the direction indicated by the arrow in FIG. 5C). More specifically, the flat portion 24 (the portion shown by the broken line in FIG. 5C) is bent upward so that the bent portion is perpendicular to the winding axis direction of the winding portion 21. As a result, an embedded portion 240 that is inclined with respect to the winding axis direction of the winding portion 21 and a terminal portion 242 that is orthogonal to the winding axis direction of the winding portion 21 are formed in the flat portion 24.

[0070] Also, the flat portion 24 of the lead-out portion 22b is bent at two locations. First, at the boundary portion 27a between the base end portion 23 and the flat portion 24, the horizontally extending flat portion 24 (see FIG. 5B) is bent upward. As a result, as shown in FIG. 5C, the flat portion 24 extends obliquely upward with respect to the base end portion 23. Further, for example, on the winding portion 21 side rather than the center in the extending direction of the flat portion 24, the flat portion 24 (the portion indicated by the broken line in FIG. 5C) is bent downward. More specifically, the flat portion 24 (the portion indicated by the broken line in FIG. 5C) is bent downward so that the bent portion is perpendicular to the winding axis direction of the winding portion 21. As a result, an embedded portion 240 inclined with respect to the winding axis direction of the winding portion 21 and a terminal portion 242 orthogonal to the winding axis direction of the winding portion 21 are formed on the flat portion 24.

[0071] Next, the wire 20 shown in FIG. 5C is placed in the cavity of a mold (not shown), and a core material containing a magnetic material and resin is filled into the cavity. At this time, the winding portion 21 is embedded in the core material, the embedded portion 240 is embedded in the core material, and the core material is filled into the cavity such that the terminal portion 242 is exposed from the core material. Next, the core material filled in the cavity is compressed and cured at a predetermined mold temperature for a predetermined time to form the core 10 shown in FIG. 5D.

[0072] Next, for example, the terminal portion 242 exposed from the core 10 is irradiated with a laser to peel off the coating on the surface of the terminal portion 242. Next, as shown in FIG. 5E, a plating layer 30 is formed on the terminal portion 242 exposed from the core 10. In the present embodiment, the plating layer 30 is formed on the inner surface 25 (FIG. 4A) and the outer surface 26 (FIG. 4A) of the terminal portion 242, but the plating layer 30 may be formed only on the outer surface 26 of the terminal portion 242. The plating layer 30 is not particularly limited, but is, for example, Sn-Pb plating (solder plating). The method of forming the plating layer 30 is not particularly limited, but is, for example, electroless plating, electrolytic plating, or dipping. Note that the step of forming the plating layer 30 on the terminal portion 242 may be performed before the molding of the core 10 (before the step shown in FIG. 5D).

[0073] Next, as shown in FIG. 4A, at the periphery of the boundary portion 27b between the embedded portion 240 and the terminal portion 242, the terminal portion 242 of the lead-out portion 22a is bent with respect to the embedded portion 240 toward the third side surface 13 of the core 10 (see the figure shown by the two-dot chain line in FIG. 4A). Thereby, the side portion 244 of the terminal portion 242 is arranged along the third side surface 13. Also, at the periphery of the boundary portion 27b between the embedded portion 240 and the terminal portion 242, the terminal portion 242 of the lead-out portion 22b is bent with respect to the embedded portion 240 toward the fourth side surface 14 of the core 10. Thereby, the side portion 244 of the terminal portion 242 is arranged along the fourth side surface 14.

[0074] Next, the tip of the terminal portion 242 arranged along the third side surface 13 is bent toward the mounting surface 15 of the core 10. Thereby, the mounting portion 246 of the terminal portion 242 is arranged along the mounting surface 15. Also, the tip of the terminal portion 242 arranged along the fourth side surface 14 is bent toward the mounting surface 15 of the core 10. Thereby, the mounting portion 246 of the terminal portion 242 is arranged along the mounting surface 15. In this way, the coil device 1 can be manufactured.

[0075] As shown in FIG. 4A, in the coil device 1 of the present embodiment, the embedded portion 240 extends obliquely from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. Therefore, as it approaches the side surface of the core 10 (or as it moves away from the base end portion 23), the embedded portion 240 moves away from the winding portion 21, and the distance between the embedded portion 240 and the winding portion 21 (the distance along the Y axis) becomes longer. Thereby, it is possible to prevent the occurrence of a short-circuit defect between the embedded portion 240 and the winding portion 21.

[0076] Further, the terminal portion 242 is exposed from the core 10 at the central portion of the side surface of the core 10 (the third side surface 13 or the fourth side surface 14) in the direction perpendicular to the mounting surface 15 (Z-axis direction). And the terminal portion 242 extends from the central portion of the side surface of the core 10 toward the mounting surface 15. Therefore, it is easy to secure the area of the terminal portion 242 (i.e., the side portion 244) disposed on the side surface of the core 10, and it is easy to form a solder fillet on the terminal portion 242 (side portion 244) disposed on the side surface of the core 10. Thereby, the mounting strength of the coil device 1 can be ensured.

[0077] Also, when the terminal portion 242 is exposed from the core 10 at the central portion of the side surface of the core 10 (the third side surface 13 or the fourth side surface 14), compared with the case where the terminal portion 242 is exposed from the core 10 at the lower portion of the side surface of the core 10, it is easier to bend the terminal portion 242 toward the side surface of the core 10 with respect to the embedded portion 240. Thereby, the manufacturing of the coil device 1 can be facilitated. Further, when the terminal portion 242 is exposed from the core 10 at the central portion of the side surface of the core 10, the DC resistance of the coil device 1 can be reduced compared with the case where the terminal portion 242 is exposed from the core 10 at the upper portion of the side surface of the core 10.

[0078] Also, the embedded portion 240 extends from the base end portion 23 to the central portion of the winding portion 21 in the direction perpendicular to the mounting surface 15 (Z-axis direction). Therefore, the center of gravity of the wire 20 (winding portion 21) is stabilized. Thereby, in the manufacturing process of the coil device 1, for example, when the wire 20 is placed in a mold and compression molded, displacement of the wire 20 can be prevented.

[0079] Also, the embedded portion 240 extends obliquely from the base end portion 23 to the side surface of the core 10 (the third side surface 13 or the fourth side surface 14) without bending at a right angle. Therefore, the DC resistance of the coil device 1 can be reduced. Also, damage to the embedded portion 240 caused by bending can be prevented.

[0080] Further, the base end portion 23 has an inclined portion 230. And in a cross section (YZ cross section) perpendicular to the mounting surface 15 and the third side surface 13, the thickness of the inclined portion 230 becomes thinner as it approaches the flat portion 24. By providing the inclined portion 230 at the base end portion 23, compared with the case where the inclined portion 230 is not provided at the base end portion 23 (that is, when the thickness of the base end portion 23 suddenly or steeply becomes thinner at the boundary portion 27a between the base end portion 23 and the flat portion 24), the DC resistance of the coil device 1 can be reduced.

[0081] Also, the lead-out portion 22a is bent at the boundary portion 27a between the base end portion 23 and the flat portion 24. And the radius of curvature of the lead-out portion 22a at the boundary portion 27a is larger than the thickness of the flat portion 24. Therefore, as it approaches the side surface of the core 10 (the third side surface 13 or the fourth side surface 14) (or as it moves away from the base end portion 23), it becomes easier to obliquely draw out the embedded portion 240 from the base end portion 23 toward the side surface of the core 10 so that the embedded portion 240 moves away from the winding portion 21. Therefore, it becomes easier to secure the distance between the embedded portion 240 and the winding portion 21, and it is possible to effectively prevent the occurrence of a short circuit failure between the embedded portion 240 and the winding portion 21.

[0082] Also, the wire 20 is a round wire or a rectangular wire wound edgewise (in this embodiment, a round wire), and the winding portion 21 has an insulating coating layer. Therefore, the lead-out portion 22a is likely to be flattened, and it becomes easier to form the flat portion 24 on the lead-out portion 22a. Also, the insulating coating layer can insulate the winding portion 21 from the magnetic material constituting the core 10.

[0083] Also, when viewed from a direction perpendicular to the mounting surface 15 (Z-axis direction), the shape of the outer peripheral surface of the winding portion 21 is circular. Therefore, as shown in FIG. 1A, when the core 10 has a first side surface 11 and a second side surface 12 facing in the X-axis direction, and a third side surface 13 and a fourth side surface 14 facing in the Y-axis direction, the following effects can be obtained. That is, in this case, as shown in FIG. 3, when viewed from a direction perpendicular to the mounting surface 15, the distance along the X-axis direction between the outer peripheral surface of the winding portion 21 and the first side surface 11, and the distance along the X-axis direction between the outer peripheral surface of the winding portion 21 and the second side surface 12 are likely to be equal. Also, the distance along the Y-axis direction between the outer peripheral surface of the winding portion 21 and the third side surface 13, and the distance along the Y-axis direction between the outer peripheral surface of the winding portion 21 and the fourth side surface 14 are likely to be equal. Therefore, the volume of the core 10 filled between the outer peripheral surface of the winding portion 21 and the first side surface 11, and the volume of the core 10 filled between the outer peripheral surface of the winding portion 21 and the second side surface 12 are likely to be equal. Also, the volume of the core 10 filled between the outer peripheral surface of the winding portion 21 and the third side surface 13, and the volume of the core 10 filled between the outer peripheral surface of the winding portion 21 and the fourth side surface 14 are likely to be equal. Thereby, the inductance characteristics of the coil device 1 can be improved.

[0084] Also, in the present embodiment, as shown in FIG. 5C, before the step of compression molding the core material (FIG. 5D), forming is performed on the flat portion 24 so that an inclined embedded portion 240 is formed in the flat portion 24. By installing the wire 20 thus formed in a mold and compression molding the core material in the mold, it is possible to effectively prevent the displacement of the wire 20 during compression molding.

[0085] (Second Embodiment) The coil device 1A of the second embodiment shown in FIG. 6A has the same configuration as the coil device 1 of the first embodiment, except for the following points. The same reference numerals are given to the parts overlapping with the coil device 1 of the first embodiment, and the detailed description thereof is omitted.

[0086] The coil device 1A has a wire 20A. The wire 20A has a winding portion 21A. The extending direction of the winding axis O of the winding portion 21A (the winding axis direction of the winding portion 21A) is inclined with respect to the direction perpendicular to the mounting surface 15 (Z-axis direction). Also, the winding axis direction of the winding portion 21A is inclined with respect to the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. Also, the winding axis direction of the winding portion 21A is inclined with respect to the mounting surface 15 and the mounting opposing surface 16.

[0087] The inclination angle θ of the winding axis direction of the winding portion 21A with respect to the direction perpendicular to the mounting surface 15 (Z-axis direction) is not particularly limited, but for example, 0° < θ ≤ 70°, 5° ≤ θ ≤ 60°, or 10° ≤ θ ≤ 50°. The same applies to the inclination angle θ of the winding axis direction of the winding portion 21A with respect to the side surface (the third side surface 13 or the fourth side surface 14) of the core 10.

[0088] In the present embodiment, the top surface 210a of the winding portion 21A is inclined with respect to the mounting surface 15. Also, the bottom surface 210b of the winding portion 21A is inclined with respect to the mounting surface 15. However, as shown in FIG. 6B, the top surface 210a of the winding portion 21A may be parallel to the mounting surface 15. Also, the bottom surface 210b of the winding portion 21A may be parallel to the mounting surface 15.

[0089] As shown in FIG. 6A, the embedded portion 240 is drawn out obliquely from the base end portion 23 toward the central portion in the Z-axis direction of the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. The extending direction of the embedded portion 240 is orthogonal to the winding axis direction of the winding portion 21A. However, in the present embodiment, the “orthogonal” is not limited only to strict orthogonality (that is, the extending direction of the embedded portion 240 intersects the winding axis direction of the winding portion 21A at 90°), and a state where it is deviated by several degrees (not particularly limited, for example, 3 degrees) or less with respect to strict orthogonality is also included in the concept of “orthogonal”.

[0090] Also in this embodiment, the same effects as those of the first embodiment can be obtained. In addition, in this embodiment, the winding axis direction of the winding portion 21A is inclined with respect to the direction (Z-axis direction) perpendicular to the mounting surface 15. Therefore, even if the embedded portion 240 is not bent obliquely with respect to the base end portion 23 (or even if the bending angle of the embedded portion 240 with respect to the base end portion 23 is small), the embedded portion 240 can be inclined toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10 according to the inclination angle of the winding axis direction of the winding portion 21A. As a result, the embedded portion 240 extends obliquely from the base end portion 23 toward the side surface of the core 10. Therefore, the distance (the distance along the Y-axis) between the embedded portion 240 and the winding portion 21A is ensured, and the occurrence of a short-circuit failure can be prevented between the embedded portion 240 and the winding portion 21A.

[0091] Further, according to the inclination angle of the winding axis direction of the winding portion 21A, the embedded portion 240 can be inclined toward the side surface of the core 10 so that the terminal portion 242 is exposed from the core 10 at the center of the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. Then, in the direction (Z-axis direction) perpendicular to the mounting surface 15, the terminal portion 242 can be arranged from the center of the side surface of the core 10 to the mounting surface 15. As a result, it becomes easy to secure the area of the terminal portion 242 (that is, the area of the side portion 244) arranged on the side surface of the core 10, and it becomes easy to form a solder fillet on the terminal portion 242 (side portion 244) arranged on the side surface of the core 10. Therefore, the mounting strength of the coil device 1A can be ensured.

[0092] The present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the present disclosure.

[0093] In each of the above embodiments, the application example of the present disclosure to the inductor has been described, but the present disclosure may be applied to other coil devices.

[0094] In each of the above-described embodiments, the entire region from one end to the other end in the extending direction of the embedded portion 240 shown in FIG. 4A or the like extends obliquely from the base end portion 23 toward the side surface (the third side surface 13 or the fourth side surface 14) of the core 10. However, it is not always necessary for the entire region in the extending direction of the embedded portion 240 to extend obliquely from the base end portion 23 toward the side surface of the core 10. For example, a portion that does not extend obliquely from the base end portion 23 toward the side surface of the core 10 may be included between one end and the other end in the extending direction of the embedded portion 240. That is, at least a part of the extending direction of the embedded portion 240 may extend obliquely from the base end portion 23 toward the side surface of the core 10.

Explanation of Reference Numerals

[0095] 1…Coil device 10…Core 11…First side surface 12…Second side surface 13…Third side surface 14…Fourth side surface 15…Mounting surface 16…Mounting opposing surface 17a, 17b…First recess 18a, 18b…Second recess 19…Chamfered portion 20, 20A…Wire 21, 21A…Winding portion 210a…Top surface 210b…Bottom surface 22a, 22b…Lead-out portion 23…Base end portion 230…Inclined portion 231a, 231b…Inclined surface 232…Non-inclined portion 24…Flat portion 240…Embedded portion 242…Terminal portion 244…Side portion 246…Mounting portion 25…Inner surface 26…Outer surface 27a, 27b, 22a1, 22b1…Boundary portion 30…Plating layer

Claims

1. A core including a magnetic material and having a mounting surface and a side surface extending in a direction perpendicular to the mounting surface, a wire having a winding portion disposed inside the core and a lead portion drawn out from the winding portion, wherein the lead portion has a base end portion continuous with the winding portion and a flat portion continuous with the base end portion and flattened into a flat shape, wherein the flat portion has an embedded portion disposed inside the core and a plating layer, and a terminal portion disposed outside the core, wherein the embedded portion extends obliquely from the base end portion toward the side surface, and the terminal portion is exposed from the core at the central portion of the side surface in a direction perpendicular to the mounting surface and extends from the central portion of the side surface toward the mounting surface. A coil device.

2. The coil device according to claim 1, wherein the embedded portion extends from the base end portion to the central portion of the winding portion in a direction perpendicular to the mounting surface.

3. The coil device according to claim 1 or 2, wherein the embedded portion extends obliquely from the base end portion to the side surface without bending at a right angle.

4. The base end portion has an inclined portion, and in a cross section perpendicular to the mounting surface and the side surface, the thickness of the inclined portion becomes thinner as it approaches the flat portion. The coil device according to claim 1 or 2.

5. The lead portion is bent at a boundary portion between the base end portion and the flat portion, and a radius of curvature of the lead portion at the boundary portion is larger than a thickness of the flat portion. The coil device according to claim 1 or 2.

6. The wire is a round wire or a flat wire wound edgewise, and the winding portion has an insulating coating layer. The coil device according to claim 1 or 2.

7. The coil device according to claim 1 or 2, wherein a shape of an outer peripheral surface of the winding portion is circular when viewed from a direction perpendicular to the mounting surface.

8. The coil device according to claim 1 or 2, wherein a winding axis direction of the winding portion is inclined with respect to a direction perpendicular to the mounting surface.

Images